This invention relates to hairpieces and in particular to an base which renders the hairpiece virtually undetectable to sight and to touch. The prior art bases consist typically of a coarse mesh, in the approximate shape of a cap, to which artificial hairs are tied. Since mesh strands do not adhere well to the scalp, a base liner is sewn over a portion of the base for the purpose of adhering the base to the scalp. This base liner is typically made of a thin, hard synthetic material. It may cover the entire base, or it may cover only a strip along the base perimeter. Some bases of the prior art utilize a very fine strand mesh.
The disadvantages of these prior bases are the following. The coarse mesh is hard, and it scratches the scalp. The base liner is hard, and its edges scratch the scalp. The base liner is impermeable to moisture and air. The edge of these bases require a thick thicket of hair to hide the base edge. This thicket gives an unnatural look, and it does not cover the base edge adequately. The mesh cannot be adhered directly to the scalp. The mesh and base liner are not skin-colored. The mesh edge, at the perimeter of the base, has sharp, hard strand ends which irritate the scalp and which are very detectable to touch and sight.
Usually, the solution for a natural front hairline has been the lace front hairpiece as disclosed in U.S. Pat. No. 2,814,301. This solution has the disadvantage that it is difficult to adhere the lace base to the scalp. A liquid adhesive must be used, which requires a inconveniently long drying time and an irritating solvent. Also, the lace base extends out in front of the hairline and must be covered with make-up. Finally, the lace base is fragile.
There are two notable attempts in the recent prior art to achieve a natural hairline. The invention of U.S. Pat. No. 4,509,539 of Alfieri utilizes a mesh strengthened by ultrasonic welding. This mesh is purported to conform to the contour of the scalp, thereby eliminating the need for liquid adhesive. It is doubtful that this hairpiece would be undetectable under close visual inspection because its mesh extends slightly out in front of the hairline. Even if that were not the case, the density of hairs at the very front edge of the hairpiece would have to be high, and this would create the impression of a hard or severe front hairline. Also, it is likely that a mesh that is sufficiently stiff to press against the scalp would cause irritation to that same scalp. A final difficulty is that this front edge would be tactually noticeable; in addition, a strong wind, a hand, a strong water current, or some other object brushing against it would peel it back.
The invention of U.S. Pat. No. 4,799,502 of Kobayashi overcomes some of these difficulties. It features a zigzag shape for a mesh-formed front hairline, an idea that has been used by numerous wig makers over the years and that is not original to his patent. This mesh must also ultrasonically welded for added strength and stiffness. What may be original is a zigzag stitching just inside the front border of the mesh, of a nylon filament which is half as fine as that forming the mesh. This filament is purported to add strength to the front portion and to prevent it from loosening. This is misleading in that the only portion of the mesh strengthened by this stitching is that portion which is actually stitched. The very front portion, of a width range between 3 and 15 mm, is not strengthened by this stitching. Also, this stitching is a source of discomfort. Accordingly, invention of Kobayashi does not solve the aforementioned problems of the front edge peeling up or of tactile detectability.
Next, consider whether his invention gives a completely natural hairline appearance. It purports to overcome the hard front problem associated with a linear and close alignment of artificial hairs, by planting the hairs at appropriate intervals along the zigzag boundary. It would seem that this design would be an improvement over its prior art in this regard, but it would also seem that difficulties remain. There is nothing to prevent hairs tied at the front vertex from migrating rearward and sideward, thereby leaving exposed the very front portion near the vertex. Also, the sharp triangular geometry of the vertex makes it impossible to place a plurality of hairs where they are most needed to cover the mesh. All of the just-discussed disadvantages of both his invention and the remaining prior art will be addressed by the present invention.